1. Field of the Invention
This invention relates to a pressure-controlled valve, that is a valve whose flow path is closed when a predetermined static fluid pressure is applied to the control chamber of the valve or a valve where a predetermined differential pressure is employed to cause the valve to operate. Further, the invention relates to a pressure-controlled valve wherein the control is accomplished with a small volume of both control and controlled fluids.
2. Background of the Invention
Prior art pressure-controlled valves which are used to perform a function contemplated by the present invention have required a relatively large "hold-up volume" of the controlled fluid within the pressure-controlled valve. In such valves the valve body itself holds a substantial volume both upstream and downstream from the valve closure point. Such valves require too much "approach volume" and "discharge volume" to be useful in a system wherein the volume of controlled fluid is quite small.